<VV> Solvent Test for Heads

[Geoff Johnson]

The problem with hand-lapping valves is they establish a seal at room 
temperature.  As the Engine heats up and parts expand at unequal rates the 
seal can not work as well.  With a properly cut interferance angle valve 
job, the valve is cut at a 1 degree difference of angle from the valve 
seat.  This creates a high surface loading, on a narrow  band, that upon 
engine operation, shapes itself to a correct angle and shape.  At room 
temperature, before startup, there is only a thin area of contact, that 
may, before it has operated, allow a little tiny leak.  If you are losing 
compression on a professionally done head I would first look elsewhere such 
as rings.

-Geoff Johnson






--On Monday, April 12, 2004 9:38 AM -0400 "N. Joseph Potts" 
<pottsf@msn.com> wrote:


>      By hand, I cleaned up and lapped one head to be liquid tight, while
> the other head, which had been three-angle ground,